Audio is hard. There are lots of wires and plugs and swearing. That's why HDMI receivers, with their promises of audio and video over one cord, make us so excited.

For today's Frankenfight, two 7.1 HDMI receivers compete for that special place in our heart home theater. Onkyo's TX-SR674 is a worthy contender, but how will it fare against Denon's AVR-2307CI? Hit the jump to find out what the experts at CNET, Sound & Vision, AV Guide, Home Theater HiFi, and the Gadget Guide have to say about these two just-over-$500 systems.

Setup

The Onkyo features an automated setup system, which uses a supplied microphone to measure speaker distances, speaker levels, and to perform the Audyssey room correction. As soon as you plug the microphone in, the Onkyo goes straight into its setup menu. From there it is only a matter of following a simple set of prompts to complete the setup. (4)

One thing that I could not change was an input's name, and thus I was stuck with the generic Video 2 for my TiVo. (4)

[Denon] has the supplied mini-mike and auto-setup routine that most receivers north of about $500 feature today...after running it...I checked the results with a sound-pressure level meter against my own test sources as well as the receiver's own internal test noise. Result: very good. Channel levels were all within ±1 dB of what I'd have set manually, and crossover choices and distances were spot-on. (1)

Unlike Denon's implementation of the Audyssey system that requires the user to run the setup program six times from six different positions in the room, Onkyo's analyzes the room's acoustics from just three positions. (5)

Why HDMI?

...a digital audio cable is still required to transmit Dolby and DTS multichannel audio from the player to the receiver. But Onkyo's TX-SR674 receiver delivers all of the HDMI features one can readily expect...(Dolby Digital, DTS, CD and DVD-Audio, and uncompressed PCM soundtracks) and all HD video formats (including 720p, 1080i, and 1080p). Additionally, the TX-SR674 is capable of converting analog component, composite, and S-Video source signals to HDMI, which means you'll need to run only one cable from your video source to the receiver and another from the receiver to your TV. (5)

Through HDMI, the Onkyo takes full advantage of the new high-resolution audio formats available on Blu-ray and HD DVD.(4)

My Comcast cable box still refuses to pass signal to any component identifying itself as an HDMI repeater (will they ever deliver the promised firmware update?), and since the 2307CI does so, like nearly all A/V receivers, I was restricted to the set-top's component output... (1)

Sound

Super Speedway is an IMAX film about open-wheel racing in the U.S., and it features lots of very impressive in-car camera and sound work. This creates very loud passages where you have the engine blaring over a myriad of bumps and rattles from the road noise and the car itself. The Onkyo excelled at these scenes, giving me the dynamics one would expect from being in a race car, while resolving the subtle details of the soundfield. Overall, I was very impressed as to how well the Onkyo reproduced this movie. (4)

[The Onkyo] could in many ways hold its own relative to an expensive 200Wpc reference receiver. And in some respects actually sounded better...only at the extreme volume levels did the bigger receiver's power advantage become apparent. (6)

[The Denon] receiver sounded first-rate on every music or movie program I tried: clean, dynamic, transparent. Top-quality recordings (1)

In regard to the sound, I enjoyed the [Denon's] "Night" feature that pumps up the center channel, letting you hear characters speak to each other while keeping music and sound effects down a bit (which is great for apartments or when you have a baby sleeping elsewhere in the house). (2)

A lot of 100-watt-per-channel receivers don't feel all that powerful, but the AVR-2307CI surely did. We even subjected it to the ultimate test by running our Dynaudio speaker set to Large, because that setting generally sounds best, but makes far greater power demands. The Denon didn't mind one bit. (3)

Video

[With the Onkyo] the incoming analog signals are automatically deinterlaced—converted from 480i to 480p—if the HDMI input on the connected TV can't handle 480i resolution, something very common in HDTVs sold before 2006... (5)

[The Denon] doesn't offer de-interlacing (480i to 480p conversion), so all of the analog video remains in its native resolution...including such common devices such as VCRs, camcorders, video iPods, and older game consoles—it's 480i. Furthermore, the AVR-2307CI's onscreen display shows only at 480i resolution over the HDMI connection as well...other 480i limitations—the lack of de-interlacing and the dearth of onscreen display at HD resolutions over HDMI—mean the AVR-2307CI's HDMI compatibility is questionable with the many older and some current HDTVs that can't receive 480i video via their HDMI inputs (3)

Direct comparisons of my best video sources on their component outputs direct-to-screen versus the Denon's converted-to-HDMI version showed the converted image to be slightly—very slightly—softer and, I felt, a hair less saturated (1)

Denon cut one too many corners for those looking for robust HDMI and high-def support (3)

Extras: Neural Sound (both have)

Neural surround's primary selling point is that it is the codec being used by XM for the XMHD channels, which offer full 5.1 surround... My experience using Neural surround on the XMHD channels was generally positive...adding a nice sense of spaciousness that is often lacking in XM broadcasts.... When I used Neural [unsupported channels], everything ended up in the center channel, and it was a significant downgrade from listening in stereo or using DPL-II Music. (4)

[Denon's] iPod dock works fairly well. The audio integration is great. You just plop your iPod into it, change source to VCR2, and navigate all your iPod menus on your TV. The playlist titles and artists do get cut off as only so many characters fit on a TV screen, but I could easily find my playlist of favorites and hit play.... The iPod video integration isn't nearly as smooth...as the Denon unit can't navigate iPod Video menus on your TV...(2)

Extras: Zone 2 Speaker Outputs [both have]

Instead of the usual B speaker outputs, the [Onkyo] features stereo Zone 2 speaker outputs, which can be fed a different source—say, XM radio—while the main 5.1 system is playing a DVD. (5)

[With the Denon] there's not only a set of B speaker outputs, you can also reassign the two Surround Back channels for use as Zone 2 speakers. (3)

Winner: Onkyo TX-SR674

The Onkyo and Denon models here are very close in features and performance, but Denon's lack of 480i support over HDMI will be nothing but trouble for anyone with an HDTV that is just a few years old. The only distinct feature that could make the Onkyo better would be to support the HDMI 1.3 standard (as opposed to the 1.1 that both models here use)...and we'd take a few more HDMI inputs, too. – Mark Wilson